1. Field of the Invention
The present invention relates to a sheet transporting apparatus, and more particularly to a sheet transporting apparatus that can realize a jam disposal mechanism with simple structure and that can thereby achieve space saving.
2. Description of Related Art
Conventionally, electrophotographic image forming apparatuses, such as printers, copiers, facsimile machines, and multifunctional machines with more than one of the functions of those, are furnished with a sheet transporting apparatus for transporting an original document or recording paper sheet, for example, through a part leading from a recording paper cassette or hand-feed tray to an image forming section, or through an image reading system for reading an original document to generate image data. Such a sheet transporting apparatus is, in particular in a large-size image forming apparatus, provided with an upstream-side transport roller (e.g., a pair of transport rollers 18 as shown in FIG. 1) at an upstream-side and a downstream-side transport roller (e.g., a pair of resist rollers 19 as shown in FIG. 1) at a downstream side, and rotates these upstream-side and downstream-side transport rollers with drive motors provided for them respectively.
For example, JP-A-5-270694 proposes this type of sheet transporting apparatus, which is provided with: drive motors corresponding to an upstream-side transport roller and a downstream-side transport roller respectively; an upstream-side rotation transmission system fitted to a roller shaft integral with the upstream-side transport roller; and a downstream-side rotation transmission system fitted to a roller shaft integral with the downstream-side transport roller. In this type of sheet transporting apparatus, during an image forming process or the like in an image forming apparatus in which the sheet transporting apparatus is incorporated, the upstream-side and downstream-side rotation transmission systems transmit the rotation of the drive motors to the upstream-side and downstream-side transport roller shafts.
This makes the upstream-side and downstream-side transport rollers rotate to transport the sheet to the downstream side. Moreover, the sheet transporting apparatus is furnished with a jam disposal rotation transmission system provided with a manual operation unit for allowing, when a sheet being transported gets stuck (i.e., when a jam occurs), removal of the jammed sheet in a state where the drive motors are stationary. Such a jam disposal rotation transmission system is coupled between the upstream-side and downstream-side rotation transmission systems, and, as the manual operation unit is rotated, the rotation thereof is transmitted to the upstream-side and downstream-side rotation transmission systems to make the upstream-side and downstream-side transport rollers rotate until a downstream-side tip portion of the sheet with respect to the transport direction is transported to a predetermined position.
However, in this type of sheet transporting apparatus, the manual operation unit is located in a space between the upstream-side and downstream-side rotation transmission systems. Inconveniently, this requires a mechanism for transmitting the rotation of the manual operation unit to the upstream-side and downstream-side rotation transmission systems, complicates the structure of the jam disposal rotation transmission system, and in addition increases the installation space needed.